The present study investigates the influence of phase separated disintegration on waste activated sludge (WAS) biodegradability in a profitable manner. An effort has been taken in this study to disintegrate WAS in an economical way by deflocculating the WAS with 0.04 g/g SS of MgCl2. The bacterial cell disruption was proficient at 42 h, where floc disrupted-bacterially pretreated sludge showed prominent solubilization of about 21.4% than the bacterially pretreated sludge (10.5%). The kinetic analysis of disintegration (suspended solids (SS) reduction and particulate chemical oxygen demand (PCOD) reduction) for control, bacterially disintegrated, floc disrupted-bacterially disintegrated sludges was observed to be first order with rate constants 0.001, 0.003, 0.005 and 0.001, 0.002, 0.005 (h(-1)), respectively. The proposed method articulates the effectiveness of sludge disintegration in terms of VFA production of about 640 mg/L in anaerobic fermentation experiment. The model (exponential rise to maximum) explaining the Biochemical methane potential (BMP) assay was implemented in Matlab. 12v. The parameter estimation analysis affords an estimate of parameter uncertainty and correlation, and is obviously explains that floc disrupted-bacterially pretreated sludge showed higher biodegradability of about 0.22 (g COD/g COD) than the others. Cost estimation of the present study revealed net profit of about 27.3 USD in floc disrupted-bacterially pretreated sludge. (C) 2015 Elsevier B.V. All rights reserved.